Three-strand knitted yarn

ABSTRACT

A knitted yarn and a method and apparatus for knitting the yarn. The yarn comprises three strands arranged as two interlocked chains. Stitches in the first chain comprise first and second strands while stitched in the second chain comprise the second and third strands. Stitches in the first and second strands are formed about one reciprocating latch needle and stitches in the second and third strands are formed about a second parallel reciprocating latch needle. Each needle pulls a newly formed stitch through a preceding stitch and casts-off the preceding stitch.

United States Patent 1 Blezard et al.

[ 1 June 12, 1973 [54] THREE-STRAND KNITTED YARN [75] Inventors: RobertC. Blezard, Woonsocket;

'- William E. Millard, North Providence, both of R1. [73] Assignee:Smithfield Fibers, 1nc., Providence,

[22] Filed: Dec. 8, 1970 [2]] Appl. No.: 96,059

[52] US. Cl. 66/170, 66/195 [51] Int. Cl D04b 1/00 [58] Field of Search66/195, 193,202,

[ 56] References Cited UNITED STATES PATENTS 2,064,074 12/1936 McNamee66/169 2,213,720 9/1940 Seim 66/1 2,020,197 11/1935 Meiwald 66/169 X2,535,376 12/1950 Thompson 66/195 X 2,316,060 4/1943 Fullerton et a1.28/78 2,822,605 2/1958 Parlin 28/72 2,433,279 12/1947 Johnson 66/1953,422,641 l/1969 Skrepek et al 66/169 2,031,707 2/1936 Hanff 66/169 X3,570,482 3/1971 Emoto 66/193 Primary Examiner-Ronald FeldbaumAttorney-Elliot A. Salter and Leonard Michaelson 57 ABSTRACT A knittedyarn and a method and apparatus for knitting the yarn. The yarncomprises three strands arranged as two interlocked chains. Stitches inthe first chain comprise first and second strands while stitched in thesec- 0nd chain comprise the second and third strands.

8 Claims, 10 Drawing Figures Pmmiumz 3.73.125

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1 THREE-STRAND KNITTED YARN BACKGROUND OF THE INVENTION This inventiongenerally relates to textile manufacturing and more specifically to anovel yarn and a method and apparatus for manufacturing such a yarn.

Prior yarn manufacturing processes include drawtwisting, braiding andknitting. In draw-twisting, a positive feed mechanism supplies strandsto a drawing area at a controlled rate. A traveller on a verticallyreciprocating ring in the drawing area guides the strands onto a bobbinwhich rotates about a vertical axis. The combined motion of the bobbinand ringcauses the strands to twist asthey accumulate on the bobbin asyarn. Once the bobbin fills, an operator interrupts the process, re-

places the bobbin and transfers the full bobbin to another twistingoperation or final storage cone.

In braided yarn, a number of strands are interwoven or braided to formthe final yarn. Two sets of feed spools counter-rotate on two trackswhile paying out the strands that make up the yarn. Each spool moving inone direction passes on alternate sides of the spools moving in theother direction. As a result, each strand on one set of feed spoolsinterweaves with all other strands from the other set.

In a prior knitting manufacturing process, two stands are deposited asalternate stitches on one or two reciprocating latch needles. As eachneedle reciprocates, it draws a newly formed stitch through a precedingstitch to form an interlocked yarn.

Each of the prior twisted, braided and knitted yarns has specificcharacteristics, advantages and disadvantages. For example, twisted andbraided yarns have a substantially circular cross-section while priorknitted yarns have either a circular or rectangular crosssection. Noneof these manufacturing processes can produce a ribbon-like yarn.

Braided yarn has a greater breaking strength than equivalent twisted orknitted yarn (i.e. yarn with an equal weight per unit length). Priorknitted and braided yarns do not unravel and splay when cut. Twistedyarns do. Prior knitted yarns are manufactured at a much greater ratethan either the twisted or braided yarns. Neither the knitted norbraided yarns have an inherent internal torque which characterizestwisted yarn, so they do not tend to kink and break in use or knit on abias. A prior knitting machine can knit yarns of widely divergent sizeswhile yarn drawing and braiding machines are limited to producing asingle size of finished yarn or, at most, a narrow range of sizes.Finally, braided yarns are relatively inelastic while both twisted andknitted yarns have a certain inherent elasticity.

As is apparent, no one yarn has all the foregoing characteristics. Inthose applications where these characteristics are desirable, acompromise is made. For example, if a yarn with a maximum strength andminimum weight is desired, a braided yarn is chosen even though it isexpensive to produce and limited to a circular configuration.

Therefore, it is a general object of this invention to provide a novelknitted yarn which incorporates many advantages previously found only indifferent prior yarns.

Specifically, it is an object of this invention to provide a yarn whichcan be knitted with a thin, rectangular cross-section.

Another object of this invention is to provide a yarn which can beknitted with a breaking strength approaching that of equivalent braidedyarn.

Yet another object of this invention is to provide a yarn which can beknitted to be relatively inelastic, but which is more economical tomanufacture than braided yam.

Still another object of this invention is to provide a method andapparatus for continually knitting the novel yarn at a high rate.

A further object 'of this invention is to provide a method and apparatusadapted for knitting the novel yarn in a wide range of yarn sizes.

SUMMARY In accordance with this invention, our yarn comprises threestrands arranged in two interlocked chains. Successive stitches in eachchain comprise two strands with one strand being common to both chains.

This yarn is produced by feeding the strands to a pair of generallyparallel, counter-reciprocating latch needles. As the first latch needlemoves in one direction, a yarn feeding mechanism loops the first andthird strands around that needle to form a stitch for the first chain.At the same time, the second latch needle pulls a first stitchpreviously formed in the second and third strands through a precedingstitch formed on that needle to form another portion of the secondchain. The knitting machine feeds the strands to the latch needles andcounter-reciprocates the latch needles to draw stitches throughpreceding stitches in each chain and cast off the preceding stitches toform the yarn.

Our knitted yarn has a number of important advantages. It is possible tovary the cross-section of the yarn by adjusting or varying the tensionapplied during the knitting operation, the spacing between the needlesor the size of strands fed to the knitting machine. If, for example, thefirst and third strands are heavy and fed under greater tension than thesecond strand, the machine tends to knit a ribbon-like yarn. The effectis also produced by increasing the spacing between the needle anddecreasing the tension to the second strand by increasing its feed rate.On the other hand, a yarn has a generally circular configuration whenthe tension on the second strand is increased or the needles are closelyspaced, or both. This yarn has a breaking strength which has the sameorder of magnitude as braided yarn. It is significantly stronger thanprior knitted yarn.

As neither the strand supply nor yarn take-up operations are involved inthe knitting sequence directly, the system is capable of manufacturingyarn at significantly higher rates than those available with eitherdrawtwisting or braiding.

This invention is pointed out with particularity in the appended claims.

A more thorough understanding of the above and further objects andadvantages in this invention may be attained by referring to thefollowing detailed description taken in conjunction with theaccompanying drawmgs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of amachine for knitting yarn in accordance with this invention;

FIG. 1A is an enlarged detail view of a portion of the machine;

FIG. 2 schematically illustrates one operating sequence for formingknitted yam;

FIG. 3 depicts the knitted yarn formed by the sequence shown in FIG. 2;

FIG. 4 schematically illustrates another operating sequence for formingknitted yarn;

FIG. 5 is a front view of the knitting machine shown in FIG. 1,partially broken away;

FIG. 6 is a side elevation;

FIG. 7 is a cross-sectional view taken along line 7-7 in FIG. 5;

FIG. 8 is a view from line 8-8 in FIG. 5; and

FIG. 9 is a machine timing diagram.

DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT A. General Discussion Inaccordance with our invention, a yarn knitting machine 10 shown in FIG.1 transforms three strands from a supply location 12 into knitted yarnwhich is stored at a yarn storage location 14. Generally, storage cones16, 18, and store the strands at the storage location 12. A feedingmechanism 22 draws strands 24, 26 and 28 from the cones 16, 18 and 20through a conventional tensioning mechanism 30 for delivery to theknitting machine 10.

The feeding mechanism 22 supplies the strands 24, 26 and 28 to a singleservice bar 32 which deposits the strands as stitches about verticallatch needles 34 and 36. The service bar simultaneously oscillatesabout, and reciprocates along, a horizontal support axis to perform thisfunction, as described later. At this point, it is merely necessary tounderstand that the strand 24 forms loops or stitches solely around thelatch needle 34 and the strand 26 forms stitches only around the latchneedle 36. The service bar 32 also alternately deposits stitches of thestrand 28 around the two latch needles 34 and 36.

The latch needles 34 and 36, shown more clearly in FIG. 1A, reciprocatealong spaced, vertical needle axes in a supporting needle slider block38 below the service bar 32. The needle 34 includes a pivoted latch 40;the needle 36, a pivoted latch 42. Each time a needle reciprocates, itdraws a new stitch through a preceding stitch disposed around needlestem (44 or 46) to form finished yarn 48.

The finished yarn 48 passes through a tensioning unit 50 and take-updrive assembly 52 driven by the knitting machine 10. At this point, theknitted yarn is completed and no further processing is necessary.

B. Yarn Structure and Method FIG. 2 illustrates the sequence for forminga yarn shown in FIG. 3. In FIG. 2A, the latch needles 34 and 36 arecentered on their respective needle axes with the needle 34 movingdownwardly and the needle 36 moving upwardly. Latches 40 and 42 on theneedles are open. Previously knitted stitches 54 and 56, each comprisingtwo strands, lie around needle stems 44 and 46 below the latches 40 and42 respectively.

The service bar 32, shown schematically in FIG. 2, comprises threecylindrical guides 58, 60 and 62 for the strands 24, 28 and 26,respectively. This service bar 32 has formed the stitches 54 and 56 andwill form subsequent stitches about the needles 34 and 36 by depositingthe strands in the directions indicated by the arrows on the individualstrands. Service bar movement is such that the strands 24 and 28 formthe stitch 54 while strands 26 and 28 form the stitch 56.

Still referring to FIG. 2A, the service bar 32 is centered between theneedles 34 and 36 and disposed somewhat behind them. As it oscillates inthe plane of the FIGURE, its arc is limited so that the outer guides 58and 62 form stitches only about the needles 34 and 36, respectively,while the guide forms the strand 28 into stitches around both needlesalternately. In FIG. 2A, the service bar 32 is moving to the right inthe F IG- URE and has just deposited a stitch 64, comprising the strands24 and 28, around the needle 34 above the latch 40. At this time, theservice bar 32 does not form a stitch around the needle 36.

Next, as shown in FIG. 2B, the needle 34 reaches the lowest limit oftravel while the needle 36 reaches its upper limit. At this time theservice bar 32 is at a righthand limit. Due to its axial motion, asdescribed later, it has moved forward, or out from the FIGURE, so thatthe strands 26 and 28 now extend from the finished yarn 48 to the rearof the needle 36 and then forward above the latch 42 in front of theneedle 36.

Concurrently, the latch 40 on the needle 34 has closed and captured thenewly formed stitch 64, while the downward motion of the this needle haspulled the stitch 64 through the previous stitch 54 and, at its lowerlimit, cast the stitch 54 off. As the stitch 54 is cast-off, it forms aportion of the finished yarn 48. The tension on the finished yarn 48,produced either by its own weight or by the tensioning unit 50 (FIG. 1),assures that the stitches clear the needles 34 and 36 as they are castoff.

In FIG. 2C, the needles 34 and 36 have returned to the position shown inFIG. 2A, but the service bar 32 is at the mid-point moving to the left.In this position, the new stitch 64 formed by strands 24 and 28 liesaround the stem 44 below the open latch 40. Furthermore, the service bar32 has completely formed the strands 26 and 28 into a new stitch 66above the open latch 42 while the stitch 56 remains formed around thestem 46 below the latch 42.

During the time interval during which the needles 34 and 36 and theservice bar 32 travelled between the positions shown in FIGS. 2C and 2D,the latch 42 closed so the needle 36 pulled the new stitch 66 throughthe previous stitch 56 as the stitch 56 is cast-off. Simultaneously, theservice bar 32 has moved to its left-hand limit and begun to formanother stitch 68 with the strands 24 and 28 around the needle 34 abovethe latch 40.

The service bar 32 is midway between the needles and moving to the rightin FIG. 2E. In this position, the needle 44 is retracting downwardly andhas closed the latch 40 preparatory to drawing the next stitch 68through the stitch 64 now formed around the stem 44.

Hence, the service bar 32 forms the strands 24 and 26 into stitchesabout the reciprocating axes for the needles 34 and 36. These stitchesare formed alternately. As each stitch is formed, the service bar 32also forms the strand 28 into a stitch simultaneously with one of theother strands. As a result, the strands 24 and 28 and the strands 26 and28 form successive stitches along each of the needles with each stitch,such as the stitches 54 and 56, being pulled through preceding stitchessuch as the stitches 56 and 64.

The resulting yarn 48 shown in FIG. 3 comprises three strands 24, 26 and28. The strand 24 includes stitches 54 and 64 which are formed with thestrand 28 while the strand 26 comprise stitches 56 and 66 also formedwith the strand 28. Each stitch passes through a preceding stitch. As aresult, the strands form two chains. Successive stitches in one chaincomprise the strands 24 and 28 while successive stitches in the otherchain comprise strands 26 and 28. In this manner, the strand 28interlocks the two chains so they cannot unravel.

The yarn shown in FIG. 3 has several advantages over prior yarns. First,the configuration of the finished yarn 48 can be varied by changing therelative fineness of each strand. If the strand 28 has a significantlygreater cross-sectional area than the two strands 24 and 26, a circularyarn can result. On the other hand, if the strands 24 and 26 aresignificantly larger than the strand 28, a thin rectangular orribbon-like yarn results. These variations can be enhanced by changingthe distance between the two needle axes, or varying the tension in thestrands or both.

By virtue of this knitted configuration, the finished yarn 48 does notrun or splay when it is cut. As the production rate is dependent solelyupon the speed of the needles and the rate at which strands are fed,production rates equivalent to the prior knitting method are attained.In addition, the number of interruptions to the process are reducedbecause the supply and take-up spools form no part of the process. Ifthe strands 24 and 26 have the predominant diameter and the feed ratesare adjusted so the yarn comprises a series of tight stitches, the yarn48 is relatively inelastic and is comparable with prior braided yarns,breaking strength approaches the breaking strength for an equivalentbraided yarn.

The machine in FIG. 1 can be modified so the service bar 32 deposits thestrand 28 as closed loops or bights around each needle to form closedstitches. The sequence for forming the yarn with closed stitches isshown in FIG. 4. A reference numeral followed by a prime indicateselements which are modified with respect to FIG. 2, identical elementsbeing referred by the same reference numerals.

Referring specifically to FIG. 4A, the needles 34 and 36 aresubstantially at the mid-point of axial travel with the needle 34 movingdownwardly. The latches 40 and 42 are open. Previously knitted stitches54 and 56 lie around the needle stems 44 and 46, respectively. Thestitch 54' comprises the strands 24 and 28 while the stitch 56 comprisesthe strands 26 and 28; and the service arm has deposited a closed stitch64 around the needle 34. As a result, the strand 28 extends from thefinished yarn 48' in front of the needle 34 around the needle andcrosses itself between the needles 34 and 36 as part of the closedstitch 64'. The strand 24 merely passes around the needle 34.

In FIG. 4B, the needle 34 has moved to a bottom position with the latch40 being closed to draw the stitch 64' through the stitch 54. The stitch54' has been castoff in the FIGURE. During the interval when the needlesmoved between the positions in FIGS. 4A and 4B, the needle 36 has movedto its upper position with its latch 42 remaining open. The service bar32 has travelled to a right-hand limit and has deposited the strands 26and28 in front of the needle 36 and above the latch 42.

During the interval when the needles moved between the positions inFIGS. 4B and 4C, the service bar 32 moved to the left to a centerposition and completed the new stitch 66 around the needle 36. Thestrand 28 again extends from the finished yarn 48 to the front andaround the needle 36 above its latch 42 to a position where continuedmotion of the service bar 32 causes the strand 28 to cross itselfbetween the needles 34 and 36. That is most clearly seen in FIG. 4D,where the needle 36 is at its lower limit with the latch 42 closed. Thestitch 56' has also been cast over the stitch 66. At this point, theservice bar 32 is depositing the strand 28 in front of the needle 34again so that they strand 28 forms a closed loop or stitch.

Finally, in FIG. 4E, the stitches 64' and 66' lie around the stems 44and 46, respectively. The service bar 32 has formed the strands 24 and28 into another closed stitch around the needle 34 above the closedlatch 40 and is moving in such a direction as to lay the strand 23 infront of the needle 36 to repeat the cycle shown in FIG. 4.

It is now apparent that the yarn produced by the sequences in FIGS. 2and 4 differs in two ways. In the sequence shown in FIG. 2, the centerstrand 28 circumscribes both needles 34 and 36 while in FIG. 4, itcircumscribes each needle separately. Secondly, in FIG. 2, stitchesformed by the strands 26 and 28 are formed by passing the threads to therear of the needle 36 before completing the stitch whereas the reversedirections are produced in FIG. 4. The modification is made by varyingthe rate at which the service bar 32 reciprocates above the needles asdescribed more fully with reference to the FIGS. 5 through 9. The yarnproduced according to the sequence according to FIG. 4 is basically thesame as the yarn shown in FIG. 3 with these two modifications. Itsadvantages are similar to those advantages described or attributed tothe yarn in FIG. 3.

A selection between the yarn produced by the sequences shown in FIGS. 2and 4 depends upon several factors. These factors include the aestheticcharacteristics of the finished yarn, its end use, its required strengthand its stitch density. Still other factors include differences insliding friction of the yarn and the material forming the strands.

The sequences shown in FIGS. 2 and 4 are both adapted to use strandswhich are twisted, braided or knitted in accordance with the prior art.Alternatively, any one or combination of the storage cones 16, 18 and 20may contain yarn manufactured in accordance with this invention.Therefore, in the foregoingdiscussion, the term strand means any yarncomponent formed from fibers, filaments, or combinations of such fibersor filaments and made by prior methods or in accordance with thisinvention. Such strands may include both textile and non-textilematerials. When knitted yarn is manufactured with strands manufacturedin accordance with this invention, its relative bulk increases stillfurther.

C. The Yarn Knitting Machine Our yarn can be manufactured on a knittingapparatus shown in FIGS. 1 and 5 through 8. This specific knittingmachine embodiment is shown for knitting only oneyam. It will becomeapparent during the following discussion, however, that the knittingmachine may be easily adapted to knit tow yarns simultaneously.

Now referring specifically to FIGS. 5 through 8, the yarn knittingmachine is disposed in a housing including a horizontal support 102. Adrive motor 104 mounted on the support 102 rotates a cam shaft 106through a conventional belt and pulley system 107. The motor also drivesan input shaft 108 for a torque converter 110 through another belt andpulley system 112 driven by the cam shaft 106. The torque converter 110controls the speed of an output shaft 114. Such torque converters areknown in the art, one example being a Zero-Max torque converter,manufactured by the Zero-Max Co., Minneapolis, Minnesota. A secondaryhorizontal support 116 spaced above the support 102 carries the torqueconverter 110 so the output shaft 114 and the yarn feeding mechanism 22are aligned. A third belt and pulley system 118 links the output shaft114 and the feeding mechanism 22.

Strands 24, 26 and 28 may differ in size and be fed to the knitting areaat different rates. The yarn feeding mechanism 22 in FIGS. and 6incorporates two feeding units 120 and 122 to supply the strands.Specifically, the feeding unit 120 supplies strands 24 and 26 at onerate, while the feeding unit 122 supplies the strand 28 at a differentrate. In this specific embodiment, the third belt and pulley system 118links both the feeding units 120 and 122 so they rotate at the sameangular velocity.

With specific reference to the feeding unit 122, an idler 124 and adriving spindle 126, both of constant diameters, are mounted in parallelon a vertical support plate 128. The driving spindle 126 rotates with ashaft 130 driven by the belt and pulley arrangement 118 while anotherbelt 132 couples the roller 124 and the spindle 126.

The strand 28 is normally wrapped about the periphery of both the idler124 and driving spindle 126 several times before being fed to theservice bar 32. As the motor 104 drives the service bar 32 and theneedles 34 and 36 at constant rates, varying the angular velocity of theoutput shaft 1 14 alters the strand feed rate. That is, such a variationalters the rate at which the feeding unit 122 continuously supplies thestrand 28 to the service bar 32 each time the needles 34 and 36reciprocate.

Simultaneously, the feeding unit 120 which comprises a driving spindle134 and idler 136 feeds the strands 24 and 26. The belt and pulleyarrangement 118 also drives a shaft 138 which supports the spindle 134while another belt 140 turns the idler 136. Variations in the speed inwhich the strands 24 and 26 are fed is obtained by varying the relativediameters of the roller spindles 126 and 134. In this specificembodiment, the spindle 126 has about twice the diameter of the spindle134 to deliver the strand 28 at approximately twice the rate the strands24 and 26.

Other types of feeding units can be incorporated in the knitting machineshown in these FIGURES. Furthermore, various guides may be interposedbetween the storage location 14 and the feeding mechanism 22 and betweenthe feeding mechanism 22 and the knitting area. Such guides are known inthe art and are not shown.

As previously indicated, the service bar 32 oscillates about andreciprocates along a horizontal axis simultaneously and in synchronismwith the needles 34 and 36 which reciprocate along vertical axes to formthe stitches. The service bar 32 and both needles 34 and 36 are drivenby the motor 104 through a series of cams and levers shown in FIG. 7.

The cam shaft 106 supports two eccentric cams 142 and 144 and a pinion146 for driving an idler gear 148 mounted on a second cam shaft 150 attwice the speed of the cam shaft 106. The shaft 150, which is verticallyaligned under the cam shaft 106, carries another pair of spacedeccentric cams 152 and 154. Spacers, such as a spacer 156 locateddirectly below the earn 144, separate the cams so each is horizontallyoffset from the others.

Each cam drives a lever mounted on a pivot shaft 158 parallel to andvertically aligned over the cam shafts 106 and 150. These levers aredesignated as a service bar lever 160, a first needle lever 162, athrow-bar lever 164 and a second needle lever 166 (FIGS. 5 and 7).

The service bar 32 is mounted on a throw-bar 168 which rides in bushings170 and 172 located on opposite side-walls of the housing 100. An arm174, rigidly affixed to the throw-bar 168, supports the threehorizontally offset cylindrical guides 58, 60 and 62 on a lower flaredportion 176 of the arm 174.

The throw bar lever 164 reciprocates the throw-bar 168 along itshorizontal axis under the influence of the ,cam 144. Bifurcated fingers178 and 180 on the throwbar lever 164 support shoes 182 which engage thecam 144 at diametrically opposed portions. As the cam 144 rotates, itoscillates the throw-bar lever 164 about the pivot shaft 158. Anintegral upper arm 184 on the throw-bar lever 164 engages a yoke 186with parallel upper and lower journals 188 and 190. The upper journal188 engages the throw-bar 168 while the lower journal 190 is adapted toride on a supporting shaft 192. Snap rings 194 in circumferentialgrooves on the upper throw bar 168 capture and center the yoke 186. As aresult, the throw-bar 168 can oscillate about its axis in the yoke 186.

A pair of offset arms 196 and 198 couple the upper arm 184 and the yoke186. A transverse pin 200 through the yoke 186 between the throw-bar 168and the shaft 192, bushings 202 formed on the arms 196 and 198 and snaprings 204 provide a conventional pivotal connection between the arms 196and 198 and the yoke 186. Therefore, as throw-bar lever 164 oscillatesabout the pivot shaft 158, it reciprocates the throw-bar 168 and theattached service bar. It is apparent that the throw-bar 168 can supportanother service bar on the opposite side of the housing so the machinecan knit two yarns simultaneously.

The cam 142, the service bar lever 160 and associated linkage provideconcurrent oscillating motion for the service bar 32. Shoes 206supported by bifurcated fingers 208 and 320 on the lever 160tangentially engage the cam 142 so the service bar lever 160 oscillatesabout the pivot shaft 158. An arm 212 on the service bar lever 160extends horizontally from the pivot shaft when the lever 160 is at amiddle position to engage a linkage mechanism and oscillate thethrow-bar 168.

Specifically, a fixed link 214 is pivotally connected to the arm 212 bya pin 216 and to a crank 218 by another pin 220. The crank 218, in turn,rotates the throw bar lever 168 about its axis without interfering withaxial motion. Such connections are known. As the cam 142 rotates andelevates the arm 206, the link 214 and the crank 218 rotate thethrow-bar 168 clockwise when viewed from the service bar 32.

In this configuration with the cams 142 and 144 both mounted on the camshaft 106, the throw bar and service bar oscillate and reciprocate atthe same cyclical rate. Therefore, the service bar 32 movessubstantially circularly and produces the open stitches 'in the yarnshown in FIG. 3.

The knitting machine is easily adapted to knit the yarn in accordancewiththe sequence shown in FIG. 4. The operator merely interchanges thecam 144 and the spacer 156 and moves the shoes 182 to a lower positionon the arms 178 and 180. With this modification, the cam 144 rotates attwice the rate of the cam 142; and

the throw-bar 168 reciprocates at twice the rate it oscillates. As aresult, the service bar 32 wraps the strand 28 in a figure 8 as closedstitches about the needles 34 and 36.

The remaining cams 152 and 144 move the needles 34 and 36 in thecounter-reciprocal motion with separate, but identical needle levers 162and 166. Referring specifically to the needle lever 162, it comprises ahorizontal arm 222 which extends through an opening 224 in the housingsidewall to emerge beside the needle slider block 38 beneath the latchneedle 34. An identical arm on the needle lever 166 emerges beside theneedle slider block 38 beneath the latch needle 36. Each arm supports abushing 226 in an aperture 228.

In FIG. 1A, the needle slider block 38 comprises a body portion 230 withtwo spaced, vertical ways 232 and 234 for supporting the stems 44 and 46on the needles 34 and 36. The stems 44 and 46 terminate at elbows 236and 238, respectively. Bushings 226 in the needle levers 162 and 166individually support the elbows 236 and 238.

The needle lever 162 also comprises shoes 240 which tangentially engagethe cam 152 and oscillate the needle lever 162 about the pivot shaft158. As the bushings 228 pivotally support the needles 32 and 34, theoscillatory motion of the arm 222 on the needle 162 is translated into areciprocal needle motion as the needles slide in their respective ways.Furthermore, the cams 152 and 154 are oppositely disposed on the camshaft 150. As a result, the needles reciprocate at a rate which is twicethe oscillating rate for the throw-bar 168 and reciprocate in oppositedirections; i.e., the counterreciprocating motion.

A still more thorough understanding of the operation of the knittingmachine shown in FIGS. 1 and 5 through 8 may be obtained by additionallyreferring to FIG. 9 which illustrates machine timing at a referencetime. As shown in FIG. 9A, the cam 152 drives the needle lever 162starting at a mid-point with a positive-going trace of the resultingcurves indicating upward displacement of the needle. Simultaneously, thecam 154 oscillates the needle lever 166 to move the needle 46 downwardlyfrom a central reference position as represented by the dashed line. Asa result, both needles reciprocate sinusoidally about a mid-pointreference with respect to time at a constant rate.

FIG. 98 represents the oscillation of the throw-bar 168 and the servicebar 32 with reference to a central angular position with clockwiserotation or displacement being represented by positive-going traces. Asthe cam 142, mounted on the upper cam shaft 106, oscillates the lever160, the throw-bar 168 oscillates completely each time the needlesreciprocate twice. As a result, the service bar 32 is centered above andbetween the needles when the needles are at the midpoint position.

With reference to FIG. 9C, the cam 144 is on the cam shaft 106 to knityarn with open stitches. Reciprocation away from the housing isrepresented by positivegoing traces. In this arrangement, the lever 164reciprocates the throw-bar 168 at the same cylical rate it oscillates.The cam 144 is oriented to retract the throwbar 168 from a centerreference position at the reference time. As the needle 34 and servicebar 32 move to a limit position and return, the throw-bar 168 moves to amaximum extension. During the time the needle 36 elevates and returns toits reference point, the guide 62 travels around the needle 36 to returnto is initial position. As a result, the strand 28, deposited by theguide 62 circumscribes both axes defined by needles 34 and 36.

If the cam 144- is on the shaft 150, it is oriented so the throw-barlever 164 is at a middle position at the reference time. During theinterval when the service bar 32 swings to the left and returns to thereference point, the throw-bar 168 undergoes an entire reciprocation asshown in FIG. 9D. This operation forms a complete stitch around theneedle 34. Another complete stitch is formed around the needle 36 as theservice bar 32 swings to the right and returns to the reference point.

As the machine knits yarn in accordance with the sequence in FIGS. 2 and4, it drops downwardly to accumulate below the support plate 116 inFIGS. 1 and 8. A roller guide 270 pivoted on an arm 272 directs the yarn48 to a drum 274. Another roller 276 on an arm 278 guides the yarn 48and holds it against the surface of the drum 274. After the yarn 48leaves the drum 274, it accumulates in a final storage location 14 whichmay comprise a shipping cone or other storage device.

The plate 102 supports the drum 274 and the arms 272 and 278 below theupper plate 116. A variable speed reduction unit 288, similar to thetorque converter and coupled to the motor 104 drives the drum 274. Abelt-and-pulley arrangement 282 couples the reduction unit 281) and themotor 104 to thereby control the tension on the finished yarn incombination with the feeding mechanism 22.

In summary, our invention is directed to three related aspects of yarnmanufacture. Our knitted yarn, by virtue of its construction,incorporates many advantages heretofore found only in different yarns.Specifically, the yarn does not unravel when it is cut and has noinherent torque. One yarn seems to have a breaking strength approachingthat of an equivalent braided yarn. Another yarn may have asubstantially circular cross-section. Alternately, tension, spacing,strand dimension, or all three can be controlled to provide aribbon-like cross-section.

Both the knitting method and apparatus are flexible. A given apparatuscan produce a wide range of yarn sizes with different types of strandswith only minor modification to the apparatus. Both the method andapparatus enable production rates which are equivalent to prior knittedyarns; this rate greatly exceeds the rates available for draw-twistingor braiding.

While we have described a specific embodiment of a knitted yarn and amethod and apparatus for manufacturing the yarn, many variations arepossible. The illustrated method for manufacturing knitted yarn andapparatus describe specific elements to perform the various operations.Other elements may be substituted without significant degradation in theoverall process. For example, the drive mechanisms move the needles in acontinuous counter-reciprocating motion. The term counter-reciprocatingis also intended to cover other types of needle motion. In some machinesthe needles may reciprocate in a mutually exclusive fashion toalternately form the two chains. Therefore, it is the object of theappended claims to cover all such variations and modifications as comewithin the true spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

l. A knitted yarn comprising a first strand arranged in a plurality ofchain stitches that define a first chain, a second strand formedseparately of said first strand and arranged in a plurality of chainstitches that define a second chain, and a third strand interknittedwith said first and second strands in alternate chain stitches foruniting the chains in a knitted construction.

2. Yarn as recited in claim 1 wherein said third strand interlockssuccessive stitches in said first and second chains.

3. Yarn as recited in claim 2 wherein said first and second chainsdefine first and second longitudinal axes, said third strandcircumscribing said first and second axes.

4. Yarn as recited in claim 2 wherein said first and second chainsdefine first and second longitudinal axes, said third strand alternatelycircumscribing each axis.

5. A knitted yarn comprising three individual strands arranged in firstand second chains, said first chain including a first and second strandarranged in a plurality of chain stitches, and said second chainincluding a third strand that is interknitted with said second strand ina plurality of chain stitches, and said second strand is interknittedalternately with the chain stitches of both chains.

6. A yarn as recited in claim 5 wherein each stitch in said first andsecond chains comprises said second strand.

7. A yarn as recited in claim 6 wherein said first and second chainshave first and second axes, said second strand circumscribing both axes.

8. A yarn as recited in claim 6 wherein said first and second chainshave first and second axes, said second strand circumscribing each axis.

1. A knitted yarn comprising a first strand arranged in a plurality ofchain stitches that define a first chain, a second strand formedseparately of said first strand and arranged in a plurality of chainstitches that define a second chain, and a third strand iNterknittedwith said first and second strands in alternate chain stitches foruniting the chains in a knitted construction.
 2. Yarn as recited inclaim 1 wherein said third strand interlocks successive stitches in saidfirst and second chains.
 3. Yarn as recited in claim 2 wherein saidfirst and second chains define first and second longitudinal axes, saidthird strand circumscribing said first and second axes.
 4. Yarn asrecited in claim 2 wherein said first and second chains define first andsecond longitudinal axes, said third strand alternately circumscribingeach axis.
 5. A knitted yarn comprising three individual strandsarranged in first and second chains, said first chain including a firstand second strand arranged in a plurality of chain stitches, and saidsecond chain including a third strand that is interknitted with saidsecond strand in a plurality of chain stitches, and said second strandis interknitted alternately with the chain stitches of both chains.
 6. Ayarn as recited in claim 5 wherein each stitch in said first and secondchains comprises said second strand.
 7. A yarn as recited in claim 6wherein said first and second chains have first and second axes, saidsecond strand circumscribing both axes.
 8. A yarn as recited in claim 6wherein said first and second chains have first and second axes, saidsecond strand circumscribing each axis.